It is desirable to have a means to modify surfaces in order to impart properties to such surfaces including ease of cleaning; resistance to soiling, staining and adherence of bacteria and other unwanted deposits; water repellency; as well as appearance and textural benefits including whitening, glossiness, softness, smoothness and lubricity. While the art is replete with a myriad of products aimed at providing one or more of these benefits, there continues to be a search for improved means to deliver these benefits.
In particular, modifying surfaces to be hydrophobic, is advantageous in providing the aforementioned benefits. For example, hydrophobic surfaces tend to repel most soils and stains and would thus be easier to clean. Surfaces such as fabrics, ceramics, porcelain, glass and teeth can be hydrophobically modified for ease of cleaning and anti-staining benefits. A hydrophobic coating on fabrics, paper, leather, skin and hair would also provide desirable textural characteristics including softness, smoothness and lubricity.
Silicone oils including the polyalkylsiloxanes such as polydimethylsiloxanes (PDMS), because of their hydrophobic nature, have been suggested for inclusion for example in oral hygiene preparations to inhibit the adhesion of food particles, cellular debris and plaque precursors to teeth such as described in U.S. Pat. Nos. 5,032,387; 5,165,913; 5,057,308 all to Hill, et al. U.S. Pat. No. 5,422,098 to Rolla et al. discloses dentifrices comprising a liquid silicone oil, such as PDMS, and a fat-soluble antibacterial agent dissolved therein, which is described as being useful for protection of teeth against plaque formation due to a slow release of antibacterial agent into the saliva. However, PDMS polymers have not generally been used successfully for coating the teeth because of poor adhesion and retention of the PDMS on tooth surfaces. To improve the adherence of the silicone on surfaces, it has been suggested to modify the silicone by addition of functional groups such as carboxy, anhydride, polyol and amino groups. Such modified silicones have been suggested for modifying various surfaces; including fibers, textiles, leather, hair and skin, teeth, paper, plastic, wood, metal, glass, stone and concrete. For example, aminoalkyl silicones are described in U.S. Pat. Nos. 5,078,988; 5,154,915; 5,188,822; and 5,427,770, all assigned to Chesebrough-Ponds and in U.S. Pat. Nos. 6,153,567; 6,129,906 and 6,024,891, all assigned to Procter & Gamble. Carboxyl or anhydride group containing silicones are disclosed in U.S. Pat. Nos. 4,501,619; 4,563,347; 4,587,320; 4,944,978; 5,063,044 5,280,019, all assigned to Dow Corning; in U.S. Pat. No. 4,857,212 assigned to Toray Silicone; U.S. Pat. Nos. 4,701,269; 4,931,062; 5,702,490 and 6,007,801, all assigned to BASF; U.S. Pat. No. 4,658,049 assigned to Chisso; U.S. Pat. No. 4,844,888 assigned to Gillette; U.S. Pat. Nos. 5,248,783 and 5,296,625 both assigned to Siltech; U.S. Pat. Nos. 5,015,700 and 5,504,233 assigned to Wacker Chemie; JP Patent Publication No. 04/120014 and U.S. Pat. No. 5,210,251 assigned to Kao; U.S. Pat. No. 4,876,152 assigned to PPG; U.S. Pat. No. 4,342,742 assigned to L'Oreal and U.S. Pat. Nos. 5,536,304 and 5,888,491, both assigned to 3M. Dimethicone copolyols are disclosed in U.S. Pat. Nos. 5,759,523; 5,827,505; 5,856,282; 6,004,538 and 6,129,906 all assigned to Procter & Gamble.
Even with the substantial body of work in this area, there continues to be a search for substantive polymers that can be deposited onto surfaces to modify the characteristics of these surfaces thereby providing a variety of the aforementioned benefits thereon. The present invention thus provides surface modifying substantive siloxane polymers and compositions comprising these polymers, which find utility, for example, in applications for the care of teeth and other surfaces of the oral cavity.
Human teeth are constructed with an inner soft layer called dentin and an outer hard layer called enamel that protects the inner structure. The enamel layer of teeth is naturally a translucent white or slightly off-white color. Under typical conditions, the enamel surface is coated with a thin layer of salivary proteins called pellicle. Either the enamel or pellicle or both can be discolored or stained and present to the outside an undesirable appearance. Further, the enamel layer of teeth is largely made of hydroxyapatite mineral crystals that create a porous surface structure. It is believed that the porous nature of enamel is what allows staining components and discoloring substances to penetrate into the tooth structure making it appear stained. Tooth discoloration is either extrinsic, on the enamel/pellicle, or intrinsic, penetrating the enamel and dentin or both.
Effective cleaning of the oral cavity to ensure oral cavity health requires control of dental plaque and calculus. The formation of dental plaque and calculus is the primary source of dental caries, gingivitis, periodontal disease, and tooth loss. Dental plaque is a mixed matrix of bacteria, epithelial cells, leukocytes, macrophages and other oral exudate. Bacteria comprise approximately three-quarters of the plaque matrix. Any given sample of dental plaque could contain as many as 400 different varieties of microorganisms. This mix includes both aerobic and anaerobic bacteria, fungi, and protozoa. Viruses have also been found in samples of dental plaque.
This matrix of organisms and oral exudate continues expanding and coalesces with other plaque growths situated nearby. The bacteria synthesize levans and glucans from sucrose found in the oral cavity providing energy for the microorganisms. These glucans, levans, and microorganisms form an adhesive skeleton for the continued proliferation of plaque.
Plaque, in turn, acts as a nucleus for the formation of calculus. Dental calculus or tartar as it is sometimes called, is a deposit, which forms on the surfaces of the teeth at the gingival margin. Supragingival calculus appears principally in the areas near the orifices of the salivary ducts; e.g., on the lingual surfaces of the lower anterior teeth and on the buccal surfaces of the upper first and second molars, and on the distal surfaces of the posterior molars. Mature calculus consists of an inorganic portion which is largely calcium phosphate arranged in a hydroxyapatite crystal lattice structure similar to bone, enamel and dentine. An organic portion is also present and consists of desquamated epithelial cells, leukocytes, salivary sediment, food debris and various types of microorganisms. Developing plaque can also adhere most easily at relatively irregular surfaces, such as those afforded by calculus. As calculus matures and hardens, it becomes visibly white or yellowish in color unless stained or discolored due to the absorption of dietary chromagens. In addition to being unsightly and undesirable from an aesthetic standpoint, the mature calculus deposits are constant sources of irritation of the gingiva.
The failure to retard or stop the proliferation of plaque and calculus is detrimental to oral health. Plaque and calculus formation may lead to dental caries, gingival inflammation, periodontal disease, and ultimately tooth loss. Additionally, calculus and plaque along with behavioral and environmental factors lead to formation of dental stains, significantly affecting the aesthetic appearance of teeth. Behavioral and environmental factors that contribute to teeth staining propensity include regular use of coffee, tea, cola or tobacco products, and also the use of stain promoting oral products, such as chlorhexidine.
The present compositions comprising specific carboxy functionalized siloxane polymers provide antiplaque, anticalculus and antistain benefits by depositing a hydrophobic coating on teeth, the hydrophobic coating being retained thereon for a sufficient period of time to provide resistance to soiling, staining and adherence of bacteria and other unwanted deposits. In addition, the present compositions provide enhanced delivery and retention of oral care actives such as bleaching agents to tooth surfaces, and thus, improved whitening and stain removal.